During past several decades, new advanced composites with excellent mechanical properties have been developed and used as metal replacement. However, most composites are made using synthetic non-degradable fibers, such as carbon, aramid and glass and polymers (resins), such as polyetheretherketone (PEEK) and epoxy. They cannot be recycled or reused easily and most end up in landfills. These composites pose a serious solid waste disposal problem due to decreasing landfill space, widespread litter, and pollution of marine environments.
Bacterial cellulose (BC) produced by Acetobacter xylinum, is a promising sustainable and biodegradable fibrous material and has the same chemical structure as the plant-based cellulose. However, BC fibers have diameters in the range of a few nano-meters and display many unique properties including higher purity, higher crystallinity, higher degree of polymerization, higher tensile strength, higher modulus and strong biological adaptability (Iguchi, M.; Yamanaka, S.; Budhiono, A. (2000). Bacterial cellulose—a masterpiece of Nature's arts. Journal of Materials Science, 35 (2), 261-270; Baeckdahl, H.; Helenius, G.; Bodin, A.; Nannmark, U.; Johansson, B. R.; Risberg, B.; Gatenholm, P. (2006). Mechanical properties of bacterial cellulose and interactions with smooth muscle cells. Biomaterials, 27 (9), 2141-2149; Klemm, D.; Schumann, D.; Udhardt, U.; Marsch, S. (2001). Bacterial synthesized cellulose—artificial blood vessels for microsurgery. Progress in Polymer Science, 26(9), 1561-1603; Klemm, D.; Heublein, B.; Fink, H. P.; Bohn, Andreas. (2005). Cellulose: Fascinating biopolymer and sustainable raw material. Angewandte Chemie, International Edition, 44(22), 3358-3393; Fink, H. P.; Weigel, P.; Purz, H. J.; Ganster, J. (2001). Structure formation of regenerated cellulose materials from NMMO-solutions. Progress in Polymer Science, 26(9), 1473-1524). The BC material has been used in a variety of applications including artificial skin and blood vessel, binding agent, loud speaker diaphragms, paper, foods, textile, composite membranes, etc. (Wan et al., 2006; Fontana, J. D.; De Souza, A. M.; Fontana, C. K.; Torriani, I. L.; Moreschi, J. C.; Gallotti, B. J.; De Souza, S. J.; Narcisco, G. P.; Bichara, J. A.; Farah, L. F. X. (1990). Acetobacter cellulose pellicle as a temporary skin substitute. Applied Biochemistry and Biotechnology, 24-25, 253-264; Shibazaki, H.; Kuga, S.; Onabe, F.; Ilsuda, M. (1993). Bacterial cellulose membrane as separation medium. Journal of Applied Polymer Science, 50 (6), 965-969; Svensson, A.; Nicklasson, E.; Harrah, T.; Panilaitis, B.; Kaplan, D. L.; Brittberg, M.; Gatenholm, P. (2005) Bacterial cellulose as a potential scaffold for tissue engineering of cartilage. Biomaterials, 26 (4), 419-431). Many pure sugars have been used as carbon source for BC culture. Among them mannitol and fructose are the most common and have shown excellent results in terms of BC production (Hong, F.; Qiu, K. (2008). An alternative carbon source from konjac powder for enhancing production of bacterial cellulose in static cultures by a model strain Acetobacter aceti subsp. xylinus ATCC 23770. Carbohydrate Polymers, 72 (3), 545-549). However, cost of these sugars is high and as a result, they are not considered to be ideal for large scale BC production. As a result, many attempts have been made to obtain higher BC yields as well as to reduce the cost of the carbon sources with some success. These include konjac powder hydrolyzate (Hong, F.; Qiu, K. (2008). An alternative carbon source from konjac powder for enhancing production of bacterial cellulose in static cultures by a model strain Acetobacter aceti subsp. xylinus ATCC 23770. Carbohydrate Polymers, 72 (3), 545-549), sugarcane molasses (Keshk, S.; Sameshima, K. (2006). The utilization of sugar cane molasses with/without the presence of lignosulfonate for the production of bacterial cellulose. Applied Microbiology and Biotechnology, 72 (2), 291-296), beet molasses (Keshk, S.; Razek, T. Sameshima, K. (2006). Bacterial cellulose production from beet molasses. African Journal of Biotechnology, 5(17), 1519-1523) and processed rice bark (Goelzer, F. D. E.; Faria-Tischer, P. C. S.; Vitorino, J. C.; Sierakowski, Maria-R.; Tischer, C. A. Production and characterization of nanospheres of bacterial cellulose from Acetobacter xylinum from processed rice bark. (2009). Materials Science and Engineering, C: Materials for Biological Applications, 29(2), 546-551). While some of these sources may be used for industrial BC production in the near future, there is significant scope to further lower the cost of BC production and expand its use in many mass volume applications.
Defatted soy flour (SF) is obtained after extracting oil from the soybeans. It consists mainly of protein (52-54%), sugars (30-32%), dietary fiber (2-3%), minerals and ash (3-6%) and moisture (6-8%). The soybean is a legume species native to East Asia and is classified as an oilseed. It is an annual and economic crop and has been abundantly produced and used in some countries for over 5,000 years (Endres J. G. (2001). Soy protein products: Characteristics, nutritional aspects and utilization, revised and expanded edition. AOCS Press, pp. 4-18). Currently, it is an important global crop and provides major amount of edible oil and protein (Martin, H.; Laswai, H.; Kulwa, K. (2010). Nutrient content and acceptability of soybean based complementary food. African Journal of Food, Agriculture, Nutrition and Development, 10(1), 2040-2049). The soybean has been shown to contain decent amount of sugars, including fructose, glucose, sucrose, raffinose and stachyose (Giannoccaro, E.; Wang, Y. J.; Chen, P. (2008). Comparison of two HPLC systems and an enzymatic method for quantification of soybean sugars. Food Chemistry, 106, 324-330). Fructose, glucose and sucrose have been used as routine carbon sources for BC production in previous reports (Yang et al., 1997). It has also been reported that raffinose and stachyose could be metabolized by lactic acid bacteria (Wang, Y. C.; Yu, R. C.; Yang, H. Y.; Chou, C. C. (2003). Sugar and acid contents in soymilk fermented with lactic acid bacteria alone or simultaneously with bifidobacteria. Food Microbiology, 20(3), 333-338). However, BC has not been produced using the soy flour extract (SFE), an inexpensive by-product of SF, as a carbon source by Acetobacter xylinum. 
There is therefore a need in the art for advanced composites with excellent mechanical properties to use as metal replacements that are sustainable, biodegradable and inexpensive to produce. There is further a need in the art for inexpensive industrial BC production.